Dhofari cow’s potentiality of milk production and lactation curve

Abstract

The objective of this study was to evaluate the potentiality of Dhofari cow’s milk production and characterizing its lactation curve and its parameters together with finding out the effect of cow’s parity and season of calving on their daily milk production and lactation curve parameters. Data of 644 lactations from 64 Dhofari cows were used in this study. Nonlinear regression analysis of data used Woods model incomplete gamma function to estimate lactation parameters showed peak yield (PY), peak time (PT) and persistency percentage (PR) of 9.11 kg, 70.77 day in milk (DIM) and 75.92%, respectively. Analysis of variance t- test showed no significance (p > 0.05) between actual milk yield lactation curve and predicted yield as the estimated lactation curve goodness of fit coefficient of determination R² was 98%. Estimated lactation curve parameters a, b, and c in Woods function for the Dhofari cows breed found to be 0.454, 0.92, and 0.013, respectively. Statistical analysis confirmed the significant (p < 0.05) effect of parity on average daily milk production. Results revealed that highest means of daily milk yield were shown in 1st (7.23 ± 0.96 kg) and 8th (7.23 ± 0.96 kg) parity. Results showed significant (p < 0.05) effect of parity on lactation curve parameters (a, b and c), PY and PT. There was significant (p < 0.05) effect of season of calving on daily milk yield. The highest means were found in autumn and summer with 7.55 ± 0.27 and 7.18 ±0.61 kg/day, respectively.

Keywords: Dhofari cows, Woods model, lactation curve, peak yield, peak time, parity, season.